Ski mechanism for aircraft or other vehicles



Jl me 29, 1937. H, 5, CAMPBELL 2,085,295

SKI MECHANISM FOR' AIRCRAFT OR OTHER VEHICLES Ffiled Oct. 3, 1954 2 Sheets-Sheet l M! VE N TOR June 29, 1937. H. s. CAMPBELL SKI MECHANISM FOR AIRCRAFT OR OTHER VEHICLES 2 Sheets-Sheet ?atented june 29. 1937 sin MECHANISM FOR amcmr'r on OTHER VEHICLES Harris 3. Campbell, Willow Grove, Pa.

Application October 3, 1934, Serial No. 746,660

14 Claims.

The present, invention relates to aircraft or other vehicles which may operate on snow or ice and particularly to the running gear therefor. One of the main objects of this invention is to provide an improved ski-construction.

When an aircraft is to be operated from snow or ice it is customary to replace wheels with skis. It is an object of this invention to provide a ski mechanism which will permit a ready interchange with wheel gear and will require a minithe axle structure to assume different angular positions. It is common practice to remove these shock absorbers when skis are to be used on the machine in order that the movement of the landing mechanism with respect to the fuselage may be eliminated. This isnecessary with the usual type of ski which must be held rigid so that it will present a flat surface. to the snow or ice at all times. If the shock absorberwere not removed so as to provide a rigid structure, the ski to the position of the shock absorber, since a considerable width of the ski is in contact with the ice.

It is an object of this invention to provide a ski mounting mechanism which may be used without removal of the shock absorber mechanism and which at the same time permits the ski to assume a proper position for travel through the snow regardless of the position of the axle structure of the undercarriage. The necessity for making any alterationto the landing gear connecting structure is eliminated, thus sim= plifying the operation of changing from one type of operating gear to the other. The advantage of retaining-the shock absorber mechanism in the system while using the ski gear will be evi- Such would ride on one edge or the other according.

siderable drift without digging in on one edge, but will actually offer resistance to the side drift and will tend to "clim to the surface.

These objects are accomplished by the use of a special pivotal mounting for connecting the ski to its framework. The pivotal axis is arranged longitudinally on the ski. The actual axis in the preferred form of the invention is located below the contact surface ot the ski. Thus, instead of a complete circular pivot, the hearing which mounts the ski to its frame takes the form of an arc of a circle of sufficient length to permit movement through the range of angles required in operation. This unique arrangement eliminates any tendency for the ski to dig in when there is a side component of movement, either because of landing with drift or because of angular movement of the undercarriage axle. In contrast, the mechanism provides a stable moment which causes the ski to assume a positive angle with respect to the surface when .any side movement is present. When operating on snow this is of great advantage. Of course the pivotal mounting also permits the ski to lie flat for all angular positions of the axle mechanism when operating on hard packed snow or ice.

A further object is to provide a ski structure which can be placed upon the wheel axle and readily secured in position by the same' parts used to retain'the wheel.

Another object is to provide effective and compact mechanism for maintaining the ski inthe most eflicient position on its transverse axis (normally the axle of the wheel) during flight, but allowing the ski to assume readily the various positions which may be required in landing. This latter object is accomplished in-a simple manner by mounting the necessary stops and sprIngsEupon the flange which carries the brake when wheel gear is used.

How these and other objects incident to the invention are obtained will be clear from the following description together with the drawings in which- Fig. 1 is a. side view of an aircraft having a landing gear incorporating the present invention.

Fig. 2 is a front view of the same aircraft.

Fig. 3 is a front sectional view of a typical wheel mounting.

Y Fig. 4 is an enlarged front view of one side of the-landing gear showing the members and ski mounting.

Fig. 5 is an enlarged front view of the ski structure and mounting partly in section, taken along the line 5-5 of Fig. 6.

Fig. 6 is a side view partly in section, taken on line 66 of Fig. 5.

Fi 7 is a front sectional view of an alternative method of connecting the ski to its mounting structure, taken along line 'l-I, Fig. 8.

Fig. 8 is a section taken along line 8-6 of Fig. 7.

The craft shown in Figs. 1 and 2 consists of is made up of V-axle members, the front member 2| of V being shown in Fig. 2 and the rear member 22 in Fig. 1. A normal shock absorbing strut 23 completes the tripod structure of the landing gear. This is attached pivotally at its lower end 24 and also by pivot 25 at its upper end to strut l8. This pointis supported by brace 26. v struts 2| and 22 are also pivoted to the fuselage at 21.

For normal operation the landing gear is provided with a wheel 28 shown by dotted lines in Fig. 1, and Fig.2. The. wheel (shownin greater detail in Fig. 3) 'is mounted for rotation on stub axle 23. A brakeflange 36 is provided on axle 29 to anchor the wheel brake 3| to the axle by means of bolts 32.

In order to remove the wheel 28 the retaining collar 33 is taken off by withdrawing bolt 34 (shown also in Fig. 5). sembly including brake drum 35 and bearings 36 may then' be withdrawn from the stub axle 29. After the wheel has been removed, the brake assembly 3| can be dismounted by removing bolts- Byreference to Figs. 5 and 6, it'will readily be seen how the ski assembly is attached to the axle 29. The structure to which the ski itself is mounted consists of sleeve 31 with supporting struts 38 running angularly downwardly to fittings 39. A tie tube 40 connects the fittings 39. To mount the ski assembly on the aircraft, the sleeve 31 is slid over axle 29 and the retaining collar 33 is replaced. Welded or otherwise fastened to sleeve 31, there is a plate 4| embodyhorizontal position during flight as shown in full line position, Fig. 1. Upon landing the spring stretches to permit sleeve 31 to rotate on axle 29, so that the ski may assume a position such as 49a (Fig. 1). In flight the rubber block 46 is under compression due to the action of spring 45. The rubber block 46 allows the ski to take up a position above horizontal in case of. necessity, such as in a tail high landing upon an uneven surface. The edges 51) and 5| of plates 4| and 43 are'arranged so as to provide'adequate clearance for the necessary movements of the ski and at the same time these edges provide a stop to prevent excessive angular movement such as The complete wheel asmight occur in flight in case of failure of spring 45 Some of the chief features of the present invention are embodied in the method of mounting the ski upon the supporting structure. In order to distribute the load evenly over the width of the ski shoe 49, brackets 52' are bolted thereto. So that the ski 49 may assume different angular positions with respect to its supporting structure 38, etc., a longitudinal pivotal connection is used between the fittings =39 and bracket 52. In the preferred form of the invention, the actual longitudinal axis 53 about which the ski may oscillate is located below the bottom surface of ski 49. The moving connection takes the form of a slot 54 having curved surfaces 55 and 56 and formed in the central portion of bracket 52. The surfaces 55 and 56 are arcs of circles having their centers at point 53. A block 51 is shaped to fit inside the slot 54 and is securely fastened by bolts 58 to the fitting 39. Sufllcient clearance is left between the ends of block 51 and slot 54 to permit the angular movement of the ski required in operation. A small spring 59 is shown in Fig. 5 which tends to urge the ski so that in flight it will assumea substantiallylevel attitude, (as shown in chain dotted position 49b, Fig. 4). In Fig. 4, the full lines indicate the position of the ski and landing gearrmembers while at rest on the ground.- The chain dotted lines 49b, 2|b indicate the position assumed during flight or at the instant of contact with the ground before the weight has been transmitted to the structure, the shock 'strut 231 being in extended position. The dotted lines 490, 2|c show the landing gear in its full up position, such as upon a landing, the shock absorber strut 23c being fully compressed. Although the strut 2| and axle 31 change their angular position as they rotate about pivot 21, it should be noted that the bottom surface of ski 49 can always maintain complete contact with the surface of the snow or ice.

In moving from position 49b'to position 490 (Fig. 4) it will be seen that besides an upward travel there is also a considerable side component of movement. The action of the ski under these conditions can best be described with reference to Fig. 5. When there is movement of the ski in the direction of arnow 60 the resistance of the snow causes a force to act at the edge of the ski 49indicated by small arrow 6|. This force 6| acting above the longitudinal rotational axis 53 causesthe ski to turn slightly in the direction of arrow 62 with the result that the ski bottom assumes a positive angle with respect to the snowsiirface, thus eliminating any tendency of the ski to dig into the. snow. Also in this fashion the ski mechanism is able to operate without dimculty when a landing is made in soft'snow with considerable side drift.

Figs. 7 and 8 illustrate a joint having the same general features as that shown in Figs. 5 and6,

, but different as to details of construction. In

which are housed in bosses 6'! of fitting 64. forms a connection in which the frictional re:-

sistance is verylow since when angular movement occurs between fitting 64 and bracket 62,

rollers 65 rollon the surface of the slot or opening 63., Of course there is a slight clearance, thediameter of the roller 55 being slightly less than the width of the slot 63, so that the unloaded side of theroller will be clear when the load is applied. Centfalizing springs 68 may be used to maintain a substantially central position of the ski during flight. These springs are attached to the fitting 64 and to clips 69 held by bolts Hi.

From the foregoing description it will be evident that a number of advantages may be derived from this improved ski construction. The simple and compact mechanism for mounting the ski on the wheel axle permits ready changing from one type of landing gear to the other. By mounting the ski on a longitudinal axis, particularly of the type indicated,'the safety of the aircraft is increased, especially when landing on a rough and uneven surface or with side drift. The longitudinal'pivotal mounting also permits retaining the shock absorber mechanism for use with ski gear, thus providing greater comfort to the occupants as well as reducing the shocks transmitted to the frame and joints of the machine with consequent reduction in servicing requirements. Because of its ability to adapt itself to uneven surfaces, the ski structure stands up well under rigorous operating conditions since the flexing strains are largely obviated, not only in the ski shoe, but also in the mounting members.

It is not intended that the present invention be restricted to the specific structures shown and described, but only by the scope of the appended .claims. u

I claim:

1. For an aircraft, a landing gear having an axle member normally carrying a wheel for 1'0- tation thereon, a ski structure capable of replacing said wheel, said structure consisting of an upper axis member to mount the ski upon the axle and arranged to permit a limited angular movement thereon, a ski shoe having an elongated plan form, a supporting means interconnecting said ski shoe and said upper axis member, a pivotal connection between the ski shoe and the supporting means, said pivotal connection having an axis which lies longitudinally of the ski shoe and substantially perpendicular to the said upper axis member, said axis being located below the plane of said ski shoe.

2. For an aircraft, a landing gear having an axle member normally carrying a wheel for rotation thereon, a ski structure capable of'replacing said wheel, said structure consisting of an upper axis member to mount the ski upon the axle and arranged to permit a limited angular movement thereon, a ski shoe having an elongated plan form, a supporting means interconnecting said ski shoe and said upper axis member, a pivotal connection between the ski shoe and the supporting means, said pivotal connection having an axis which lies longitudinally of the ski shoe and substantially perpendicular to the said upper axis member, said pivotal axis further being located below a plane passing through the longitudinal edges .of said ski shoe so that a horizontal pressure upon an edge of said ski shoe causes angular movement of the shoe in a direction which raises the edge of the shoe upon which the pressure is applied.

3. For an aircraft, a landing gear having an axle member normally carrying a wheel for rotation thereon, a ski structure capable of replacing said wheel, said structure consisting of an gated plan Q axle and arranged to permit a limited angular movement thereon, a ski shoe having an elonrm, a supporting means interconnecting sald'ski shoe and said upper axis member, a connection allowing the ski shoe to assume various angular positions with respect to said supporting means, said connection having a longitudinal axis located sufiiciently' below the plane of the ski shoe that a lateral movement of the ski causes the ski shoe to tend to assume a positive angle with respect to the direction of said lateral movement.

4. For a running gear, capable of use on snow or ice, an axle structure, a ski mechanism mounted on said axle structure for limited angular movement thereon, a supporting means extending downwardly from said axle structure, a ski shoe having an elongated plan form, a connection between said supporting means and said ski shoe arranged to permit angular movement of the ski shoe with respect to said supporting means, the angular movement being about a longitudinal axis located below the plane of said ski shoe.

5. For a running gear capable of use on snow or ice, an individually sprung axle structure, a ski mechanism mounted on said axle structure for limited angular movement thereon, a supporting means extending downwardly from said axle structure, a ski shoe having an elongated plan form, a connection between said supporting means and said ski sh'oe arranged to permit angularmovement of the ski shoe with respect to said supporting means, the angular movement being about a longitudinal axis located suificiently below the plane of said ski shoe that a horizontal pressure at the edge of said ski shoe produces a turning moment about said axis tending to raise the edge of the ski shoe to which the pressure is applied.

6. For a running gear capable of use on snow or ice, an axle structure, a ski mechanism mounted on said axle structure for limited an gular movement thereon, a supporting means extending downwardly from said axle structure. a ski shoe having an elongated plan form, a connection between said supporting means and said ski shoe arranged to permit angular movement of the ski shoe with respect to said supporting means, the angular movement being about a longitudinal axis located below a plane passing through the longitudinal edges of said ski shoe so that a side component of movement causes said ski shoe to tend to rotate about said axis in a manner such that the edge of the ski toward the direction of movement is raised.

'7. In an aircraft, an axle member, a ski structure having a tubular member for mounting the ski upon said axle member, a pair of struts attached to said tubular member at spaced points and converging downwardly and forwardly, a. second pair of struts attached to said tubular member and converging downwardly and rearwardly, a'fitting attached to each pair of struts at their lower ends, a ski shoe having brackets attached thereto, said brackets being arranged to co-operate with said fittings to provide for relative motion between said ski shoe and said struts about a pivotal axis disposed longitudinally of the ski and below the plane of the ski shoe.

8. In a ski construction, a ski shoe, a supporting structure, a connection between said ski shoe and said structure comprising a fitting upper axis member to mount the ski upon the permitting relative angular movement of the ski shoe with respect to the supporting structure, an. axis about which the ski shoe rotates, said axis being located below the general plane or the ski shoe so that an edge of the ski shoe tends to raise in response to a horizontal pressure applied at that edge.

9. In a ski construction, a ski shoe. a supporting structure, a.' connection between said ski shoe and said structure providing for relative movement therebetween about a longitudinal axis, located slightly below the bottom surface of said ski shoe, said connection incorporating a fitting having an arc shaped slot whose center lies on said axis.

10. In a ski construction, a ski shoe, asupporting structure, a connection between said ski shoe and said structure providing. for relative movement therebetween about a longitudinal axis, located slightly below the bottom surface-of said ski shoe, said connection incorporating afitting having an are shaped slot whose center lies on said axis, said fitting being mounted on said ski shoe, and sliding block means shaped to flt said-slot and connected. to said structure.

11. In a ski construction, a ski shoe, a sup porting structure, a connection between said ski shoe and said structure providing for relative movement therebetween about a longitudinal axis, located slightly below the bottom surface of said ski shoe, said connection incorporating a fitting having an are shaped slot whose center lies on said axis, said fitting being mounted on said ski shoe, rolling means connected to said structure and adapted to roll in said slot.

' 12. In an aircraft, a ski structure for use with an undercarriage of the split axle type, saidski structure having a ski shoe and supporting members, said ski shoe being mounted for relative angular movement with respect to said members by means of a pivotal connection having an axis longitudinally disposed below the general plane oi the ski shoe and arranged to permit an edge of the ski shoe to raise in response to a horizontal pressure applied at that edge, and a single spring means urging the ski shoe to one extreme of its angular movement so that .the ski shoe assumes a substantially horizontal position'when the undercarriage is extended during flight.

13. For an aircraft, a landing gear having a pair of individually mounted axle structures, each of said axle structures being pivotally connected to the frame of the aircraft, a shock absorbing unit connected to said axle structure in such a manner that upon deflection of the shock absorbing unit the axle structure moves on its pivotal connection, ski mechanism mounted upon said axle structure and composed of a ski shoe and supporting structure, means incorporated in said ski mechanism for allowing its use with said pivotally connected axle structure and shock absorber unit, said means involving a connection between said ski shoe and said supporting structure providing for relative movement therebetween about a longitudinal plane of the ski HARRIS S. CAMPBELL 

